【IT168 技术文档】
Question 1:What will happen when you attempt to compile and run this code?
class Base{
public final void amethod(){
System.out.println(“amethod”);
}
}
public class Fin extends Base{
public static void main(String argv[]){
Base b = new Base();
b.amethod();
}
}
A. Compile time error indicating that a class with any final methods must be declared final itself
B. Compile time error indicating that you cannot inherit from a class with final methods
C. Run time error indicating that Base is not defined as final
D. Success in compilation and output of “amethod” at run time
Question 2: Given the following code what will be output?
public class Pass{
static int j = 20;
public static void main(String argv[]){
int i=10;
Pass p = new Pass();
p.amethod(i);
System.out.println(i);
System.out.println(j);
}
public void amethod(int x){
x=x*2;
j=j*2;
}
}
A. Error: amethod parameter does not match variable
B. 20 and 40
C. 10 and 40
D. 10 and 20
Question 3:What happens when you attempt to compile and run these two files in the same directory?
// File P1.java
package MyPackage;
class P1{
void afancymethod(){
System.out.println(“what a fancy method”);
}
}
// File P2.java
public class P2 extends P1{
afancymethod();
}
A. Both compile and P2 outputs “what a fancy method” when run
B. Neither will compile
C. Both compile but P2 has an error at run time
D. P1 compiles cleanly but P2 has an error at compile time
Question 4:Which statement declares a variable a which is suitable for referring to an array of 50 string objects?
A. char a[][];
B. String a[];
C. String []a;
D. Object a[50];
E. String a[50];
Question 5:Given the following declaration
String s = "Example";
Which are legal code?
A. s >>> = 3;
B. s >> = 2;
C. int i = s.length();
D. String t = "For " + s;
E. s = s + 10;
Question 6:What will happen when you compile and run the following code?
public class Scope{
private int i;
public static void main(String argv[]){
Scope s = new Scope();
s.amethod();
}
public static void amethod(){
System.out.println(i);
}
}
A. A value of 0 will be printed out
B. Nothing will be printed out
C. A compile time error
D. A compile time error complaining of the scope of the variable i
Question 7:What will happen when you attempt to compile and run this program?
public class Outer{
public String name = “Outer”;
public static void main(String argv[]){
Inner i = new Inner();
i.showName();
}//End of main
private class Inner{
String name = new String(“Inner”);
void showName(){
System.out.println(name);
}
}//End of Inner class
}
A. Compile and run with output of “Outer”
B. Compile and run with output of “Inner”
C. Compile time error because Inner is declared as private
D. Compile time error because of the line creating the instance of Inner
Question 8:What will be the result when you attempt to compile and run the following code?
public class Conv{
public static void main(String argv[]){
Conv c = new Conv();
String s = new String(“ello”);
c.amethod(s);
}
public void amethod(String s){
char c = ‘H’;
c+=s;
System.out.println(c);
}
}
A. Compilation and output the String “Hello”
B. Compilation and output the String “ello”
C. Compilation and output the String “elloH”
D. Compile time error
